Experimental study on the mechanical and self-sensing behaviors of prestressed carbon fiber-reinforced polymer reinforced concrete composite structures

A type of self-sensing prestressed carbon fiber-reinforced polymer reinforced concrete composite structure was proposed and studied, composed of reinforced concrete beam, prestressed carbon fiber-reinforced polymer plate, and long-gauge fiber Bragg grating sensors. The carbon fiber-reinforced polymer plate was prestressed and bonded to the bottom of the reinforced concrete beam. Two types of anchorage systems were compared and studied. The long-gauge fiber Bragg grating sensors were used as active elements for the self-sensing of mechanical responses, which were installed on the tensile rebars, carbon fiber-reinforced polymer plates, and concrete. A series of static and fatigue 4-point flexural experiments were carried out to study the bending and fatigue performances of the composite structures. After a prescribed number of fatigue loading cycles, monotonic flexural bending was performed to investigate the deterioration of properties. The results showed that the long-gauge fiber Bragg grating sensor is valid for the mechanical response sensing of the proposed structures. The compatibility of the prestressed carbon fiber-reinforced polymer plate and concrete in the pure bending zone is excellent even under fatigue loading. The load-carrying capacities were improved by more than 30% due to the application of prestressed carbon fiber-reinforced polymer plates. The stiffness was also improved remarkably and generally decreased with the accumulation of fatigue cycles linearly.